T400s faulty backlight - does changing of LED-Subcard help?

[Nebelfelsen]

Hello,

I own a Thinkpad T400s with On-Site-Service. Monday evening the backlight of the display became defective. I called the Lenovo hotline and a technician came to repair the thinkpad.

Unfortunately the hotline did not order an exchange display for the technician but a "LED subcard" which did not solve the problem. Now I have to wait for a second try of the technician to get my system repaired after he received the exchange display which he ordered today.

Lenovo told me that it is usual to try an exchange of the LED subcard first when a display backlight becomes defective.

I understand that the exchange of a display inverter card may help when you own a notebook with a usual backlighted display. But does the exchange of the LED subcard really may help when a LED backlighted display becomes defective. The technician and me suppose that the LED subcard has nothing to do with the LED backlight and is just for the status LEDs (power, sleep, hdd activity, ...). Can anyone confirm this and is Lenovo wrong when the say that it is necessary to try an exchange of the LED subcard first? Or is Lenovo right and the LED Subcard is an essential component of the display backlight?

Kind regards and many thanks in advance for any helpul hint.

[duffy]

Looks like you're correct. The LED subcard is just the small PCB that has the LEDs for the Wifi, HDD, and WAN. You can see a complete list of parts at the link below.

http://download.lenovo.com/ibmdl/pub/pc ... 271_01.pdf

[Nebelfelsen]

Thanks for your reply. I already looked into the Hardware Maintenance Manual and in deed the part that was brought by the technician was the FRU 45M2773 - the LED subcard.

But Lenovo does not want to open a complaint about this and the hotline said, that this is the usual way to replace the LED subcard first when the display backlight becomes defective. Lets hope that the display will not become defetive again after this issue - but I worry that the on-Site-Service will proceed same as now if the issue appears later again.

Can anyone confirm that the display would also work if the LED subcard is taken out?